The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
As shown in FIG. 1 representing a shift stage for each vehicle speed of Europe authorization mode with respect to a vehicle in which a manual transmission is mounted, in EUDC (Extra Urban Driving Cycle), a 6-speed shift stage can be used on an extremely short section when a vehicle speed is equal to or more than 100 kph.
Meanwhile, a trend of recent power trains for vehicles is to pursue downsizing of an engine and multi-stages of a transmission for improving a fuel efficiency.
We have discovered that a set shift stage for each vehicle speed by regulation of Europe authorization mode (New European Driving Cycle: NEDC) for the trend may be not corresponded to a shift stage for each vehicle speed which is actually used in a vehicle, thus, it may be difficult to satisfy amount of exhaust hazardous materials (Emission) and fuel efficiency condition required by the authorization mode.
For instance, FIG. 2 illustrates to compare relations between fuel efficiency and various shift ratio spans with respect to shift ratio spans of a 5-speed transmission according to Europe authorization mode, and in comparison to A, which is to be a standard at a most upper side, representing shift ratio spans of the 5-speed transmission according to Europe authorization mode, for realizing 6-speed shift stages, fuel efficiency may be relatively deteriorated in B, which is positioned immediately below, that a shift ratio section to be same to entire shift ratio span of the A is separated to 6-speed shift stages, and fuel efficiency may be provided to be same to the A in C, which is positioned next below, that 6-speed shift stages are realized such that both a low speed section and a high speed section are extended more than entire shift ratio span of the A by making each shift ratio span to be equal to the standard A, and fuel efficiency may be relatively deteriorated in D, which is positioned next below, that each shift ratio span is extended as the C, however, the high speed section is same to the A and the low speed section is more extended, and fuel efficiency may be better improved in E that each shift ratio span is extended as the C, however, the low speed section is same to the A and the high speed section is more extended.
That is, when 6 stages manual transmission as an example of transmission multi-stages for enhancement of fuel efficiency is configured, in comparison with fuel efficiency according to Europe authorization mode as the A in FIG. 2, fuel efficiency is to be substantially enhanced in case that shift ratio of only 6-stage which is a highest stage is set to be relatively low as the E and fuel efficiency performance is to be same to or less than the A in other case.
As explained above, enhancement of fuel efficiency through reduction of shift ratio and multi-stages (more than 6 speeds) in a vehicle applying a manual transmission is extremely limitative on a condition of Europe authorization mode.
The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the present disclosure falls within the purview of the related art that is already known to those skilled in the art.